Lifedoat



1943. w. E. ELLING 2,328,437

LIFEBOAT Filed April 10, 1940 4 Sheets-Sheet 1 INVENTOR Na ATTO NEY 1943- w. E. ELLING 2,328,437

LIFEBOAT Filed April 10, 1940 4 Sheets-Sheet 2 INVENTOR 'Wil/iamE. E ling Q ATTORN y 1943- w. E. ELLING 2,328,437

LIFEBOAT Filed April 10, 1940 4 Sheets-Sheet 3 .INVENTOR Aug. 31, 1943. w. E. ELLING 2,328,437

LIFEBOAT Filed April 10, 1940 4 Sheets-Sheet INV ENTOR B fh'llmmifz' [my QX \QA TORNEY N Patented Aug. 31, 1943 mun I mason William animatema s om. N. r. 'Applioatlon ApI-ll 10,1040. saw no. sza'soi v is calm. i]. 9-4) This invention relates to a new and useful improvement in lifeboats, which complies in all respects with the regulations of all of the principal maritime countries, and, in particular, those of the United States. The aim of any naval architect is to limit the top weight oi ships and, since lifeboats are usually carried on the top deck, they should be as light as possible. In recent years this has become of increased importance since the introduction of gravity acting track-andcradle davits has made it possible to greatly ln-' crease the size and capacity of lifeboats.

The thickness of the shell plating of standard lifeboats is about three sixty-fourths of an inch for boats up to 20 feet in length and three thirtyseconds of an inch for large boats. Such thicknesses are sumcient to prevent puncture by drift wood or accidental contact with other obects and any greater thickness would make the metal unsuitable for cold working with ordinary machinery. particularly since the plates are galvanized.

Lifeboats are customarily suspended from the davits by falls attached adjacent the ends. Obviously, lifeboats made of such thin plating must be stiflened not only to withstand the terrific strains and battering of heavy seas, but also to make it possible to suspend them in this way without buckling. Therefore, in the past lifeboats have usually been reinforced by a large number 01 cross-frames or bracesand by longi-' tudinal reinforcement as well, all of which adds to the weight and to the cost of construction.

Essentially, the lifeboat or this invention consists of a relatively thin sheet metal shell such as above described, of conventional shape and dimensions so reinforced by an inner hull composed of a plurality of longitudinal air-tanks, integral with the outer shell, that without additional stiffening members the boat has extreme longitudinal rigidity and requires no transverse bracing. In this way simplicity and economy of construction is combined with lightness in weight and extreme longitudinal rigidity.

Furthermore, the air-tanks forming the inner hull are so associated that they form a bank of longitudinal seats on either side of the boat so that a large part of the seating capacity is supplied without additional structure and which, when supplemented by transverse thwarts, provide a very large total seating capacity without unduly raising the center of gravity or impairing the stability of the boat. In addition, the

that the interior of the boat is substantially v; shaped. This is very important because. very fre- I quently fully loaded lifeboats are filled with water. A lifeboat constructed in accordance with this invention is-not' only buoyant, and very stable when so loaded and filled, but is selfbailing under the action of the wavesto an extent which renders tirely practicable.

A further advantage of a lifeboat of this invention is that-it is rat-proof, there being no recesses or spaces behind the air tanks or elsewhere in which rats can hide. This is of great practical importance because whenever a vessel enters a harbor it is inspected by health oflicers, and if rats are found, fumigation at very considerable expense and inconvenience is required. Old style lifeboats with air tanks separate from the shell are always an object of great suspicion in this respect, due to the many unavoidable recesses behind the tanks in which rats can hide.

The proper upkeep of the lifeboat of this invention is easier, less expensive and more certain, since all of the surfaces which require painting are fully exposed and easily reached so that they may be painted by the ship's crew while at sea, whereas this is not possible with lifeboats having separate air tanks because the removal of such tanks from the interior of the boat while at sea is, of course, not allowed. Also, the fact that the exposed surfaces of the tanks forming opposite sides of the inner hull are flat, straight, and, as a general rule, parallel to each other, makes it possible to pre-fabricate many of the interior fittings, such as the thwarts, storage tanks for water and food, etc., at a considerable saving in cost of construction and assembling, and to vary the positions of these fittings, if desired, without altering their dimensions.

Other practical advantages of the lifeboat of this invention will be recognized and appreciated by those skilled in the art.

Lifeboats embodying this invention are shown in the drawings, of which- Figure 1 is a longitudinal vertical section of a lifeboat upon the line l-l of Figure 2, viewed as indicated by the arrows;

Figure 2 is a plan view of the same lifeboat;

Figure 3 is a transverse vertical section on the line 3-3 of Figure 2 viewed as indicated by the arrows;

Figure 4 is a longitudinal vertical section of a arrangement of the longitudinal air tanks is such as lifeboat oi sligh y modified o truction on the additional manual bailing enline H oi Figured, viewed as indicated by the arrows;

Figure 5 is a plan view of this lifeboat;

Figure 8 is a transverse vertical section through this lifeboat at the line -6 of Figure 5, viewed as indicated by the arrows;

Figure 7 is a transverse vertical section of another lifeboat embodying the invention illustrating another modification in structure;

Figure 8 is a fragmentary transverse vertical section of a lifeboat illustrating a further modiiication of structure;

Figure 9 is a fragmentary cross-section of a lifeboat illustrating still another modification of hull structure;

Figures 10 and 11 are, respectively, a longitudinal vertical section and a'fragmentary plan view of the lifeboat of Figure 9;

Figures 12 and 13 are schematic illustrations of a midship section of the lifeboat of Figures 1-3 showing certain structural and functional characteristics; and

Figure 14 is a diagrammatic illustration of means for testing the inner hull for air tightness and the presence of water therein.

The lifeboat illustrated in Figures 1-3 consists of a sheet metal outer shell I of conventional shape, a keel 2 and gunwales 3 which may be of angle-bar and, if desired, air tanks 4 and fitted into the bow and stem, respectively.

The boat is divided transversely by a plurality of sheet-metal partitions or bulkheads 6, three being shown in Figures 1 and 2, the inner edge of each of which has a step-like configuration as best seen in Figure 3. Using these bulkheads 6 as ends and the outer shell I as a side, sheetmetal, straight, flat-surfaced air tanks are constructed by riveting or welding so that an innerhull is formed consisting of three interconnected tiers I, 8 and 9 of subdivided air tanks. all parts of which are of flat sheet-metal excepting the side formed by the outer shell I extending the length of the boat until they merge with the inwardly curving bow and stern.

As will be evident from Figure 3, these tanks also form girder-like structures extending substantially the length of the boat and they stiffen and support the outer shell to such an extent that no other longitudinal or transverse reinforcement or bracing is required to enable the boat to withstand the severe strains of launching when loaded or the battering of heavy seas.

The strength of such a boat may be calculated by a formula giving the moment of inertia. In view of the fact that it is not possible to keep a boat on an even keel, the moment of inertia should be the same in any heeled-over position. To accomplish this without increasing the thickness of the shell plating the plates forming the common walls of adjacent tanks such as those at M in Figure 3 are preferably so arranged that they lie approximately in planes which intersect the center line of the boat at approximately gunwale height. Plates so positioned and joined to the upper and inner edges of the riser and seat plates, respectively, form a highly efficient stiffening system even though constructed of very thin plating.

It is a known fact that a beam girder which is supported at the ends is subjected to compression in the top member and tension in the lower memper. In lifeboats these members are necessarily made of very thin sheet metal. This does not impair the eifectiveness of the tension or lower member, but the upper member, which is acting as a strut must he formed as to be able to sustain a compression stress equal the maximum tension in the lower member. The construction just described conforms to this requirement. A sheet metal life-boat with a sheet metal inner hull constructed in this way and having no other stiiienersis strong enough to support a load of 83,500 pounds, including the weight of the boat itself, between two hoisting points 33 feet apart with a safety factor of 6. the section of modulus being 496 in. 3. In an actual test of a boat of this type with the hoisting points 30 feet apart and containing a load oi 32,000 pounds, the deflection in that length was only three-thirty-seconds of an inch.

Also, this construction provides several long flat seats l0, II and i2, on each side of the boat progressively stepped downwardly from adjacent the gunwale towards the center. These seats preferably have a slight downward slope to insure drainage. 2

Additional seating capacity is provided by thwarts i3 extending between and attached to the inner edges of the upper tier of tanks and positioned above the transverse partitions 6, by thwarts ll bridging the space between and attached to the upper inner edges of the intermediate tier of tanks and positioned between thwarts l3 as shown in Figure 2, and by footboards l5 extending between the lowest tier of tanks. With this arrangement passengers may sit facing the center of the boat on each tier of tanks with their feet on the top of the tier below; other passengers mayslt facing lengthwise of the boat upon thwarts IS with their feet on thwarts ll, still other passengers may sit on thwarts H with their feet on foot-boards i5, and, if necessary, other passengers facing the center of the boat upon foot-boards IS with their legs extending down through openings i6 into the bilge. When such a boat is loaded the first passengers to enter will instinctively step down to the lower and most central seats so that the center of gravity remains low and the stability of the boat maintained even during the difllcult operation of loading. Furthermore, if any water enters the boat, it will collect in the bilge, which, as already explained, is at the center of the bottom, so that it tends to increase rather than impair the stability. of the boat. To insure that the bilge water is uniformly distributed throughout the length of the boat, partitions 6 are provided with openings II adjacent the keel.

In order to conform to the regulations of the Bureau of Marine Inspection and Navigation the height of the gunwale must not be more than 45% of the beam of the boat. If this specification is followed and if the tiers of air-tanks are so proportioned that an imaginary line drawn from the keel to the gunwale passes through the riser and top of each tank of each tier, the boat if it rolls 20 from the horizontal when fully loaded and filled with water, which it may easily do, will discharge over the gunwale substantially all the water in the boat except that between the imaginary line referred to above and a line drawn 20 from the horizontal and intersecting the gunwale.

In Figures 12 and 13 the imaginary line between the gunwale and the keel is shown at l8, and the imaginary line representing a 20 displacement from the horizontal is shown at l9. As the imaginary line l8 becomes horizontal through the heeling-over of the boat by 20 as illustrated by Figure 13, whatever water there is in the boat above line llwill be discharged overboard, leaving only the relatively inconsiderable amount in the area between lines l8 and I 3, which, it will be noted, is wedge-shaped, with its greatest mass adjacent the center line of the boat, where it serves as ballast rather than a disturbing factor. When the boat rights itself, this water can be bailed out by hand without undue difllculty, or if left in the boat it would add to the stability.

It will be realized from the above description that the lifeboat of this invention will have great stability even when heeled over at, say, an angle of 20. This is also illustrated diagrammatically by Figure 13. The center of gravity of the hull and passengers of the heeled-over boat is at 20. The center of the water load is at 2|, and the total center of gravity at 22. Gravity acts straight downward, as indicated by the arrow 22a. The center of buoyancy is at 23 and acts upwardly, as indicated by the arrow 24. The center of buoyancy 23 is well outside the center of gravity 22, and will remain so irrespective of the degree to which the boat is heeled over. Therefore, both the pull of gravity and the lift of buoyancy work together to restore the boat to an even keel.

This is not'so with respect to a lifeboat having an outer hull identified with that of the boat of this invention, but lacking the inner hull because in that case when mass of water rushes to one side away from the center line of the boat so that the center of gravtiy also shifts rapidly in the same direction and may well overtake or pass outside of the center of buoyancy, with the result that the downward pull of gravity and the upward lift of buoyancy tend to capsize the boat instead of right it. a

,The construction of the tanks which form the inner hull may be carried out in any way desired, but preferably the sheet metal plates should be so applied that all of the riveting or welding may be done in the open and not through manholes in an otherwise closed space. This insures a thorough-going construction and very consid the boat heels over the 'erably reduces the cost of manufacture. It will be evident to those skilled in the art that sheetmetal tanks, the sides of which are bent and flanged as indicated in the drawings, may be put together in this simple and inexpensive way.

There is no limit in the size of the lifeboats, which may be made of comparatively thin sheet metal and fitted with longitudinal radial girder plates forming an inner hull and providing an abundance of longitudinal strength. The International Convention for the Safety of Life at Sea of 1929 has fixed the liimt of weight of fully equipped and manner lifeboats at 20 tons of 2240 lbs. each, but this ruling may well be revised in view of the great factor of safety given to boats of even, larger size if constructed with the longitudinal ner hulls of my invention.

The lifeboat illustrated in Figures e, and 6 is similar in all essential respects with that described above. The inner hull is composed of two tiers of air tanks 25 and 28 instead of three, which of course reduces the seating capacity and also to some degree the reinforcement of the outer shell provided by the inner hull. Such a boat may have a length of about 30 feet and a' capacity of approximately 85 persons. As in the boat first described, there are transverse thwarts 21 extending between the upper edges of the upper tier of tanks 25 and positioned above the transverse partitions B, of which four are shown, and other tanks 23, which serve not only as seats for passengers, but also as foot-boards for those sitting upon the uppermost thwarts. In addition, a foot-board 23 is provided for the feet of those sitting on the lower tier of tanks and on the thwarts 28.

In the construction shown in Figure 8, the tops and risers of the upper tier of tanks 30 and the dividing partitions and tops of the two lower tiers of tanks, 3| and 32, are formed of single, suitably-bent plates, as distinguished from the construction shown in Figure 3, in which the dividing partitions and risers for the two upper tiers of tanks and the risers and top of the lower tier of tanks are each composed of a single plate bent to shape.

Still another modification of the lifeboat of this invention is shown in Figure 7. In this there are two tiers of tanks, 33 and 34, on each side, the lower 33 of which is integral with the outer shell, but the upper 34 of which is separate and fitted against the side in any suitable way, as, for example, suspended by means of hangers from a longitudinal bench 36 running lengthwise in the boat adjacent the gunwale. If these tanks are proportioned in accordance with the specifications already laid down, the boat will have substantially the same stability as that of Figure 6, but this construction, though simpler and less expensive, is inferior because as a practical matter separate tanks cannot be fitted to the hull with sufiicient accuracy to avoid spaces large enough for rats to hide in.

Lifeboats having double bottoms at a level above the outside water level have not proven satisfactory because even if there are scupper pipes for draining, if water breaks over the gunwales in considerable amount, it would rush towards the sides, rendering the boat unstable.

The boat of my invention, having one built-in straight longitudinal tank on each side, resembles a double bottom boat somewhat, but the open space at the center of the boat formed by the two straight inclined plates constituting the risers of the tanks, provides an area directly above the keel where incoming water can gather. This in an important feature because as already explained the water gathering here will outbalance any water which may rush to the side of the boat.

Figures 9, 10 and 11 illustrate a lifeboat built in accordance with this invention in which each half of the inner hull is composed of four longitudinal tanks, 41, 48, 49 and 50, an excellent construction for lifeboats of larger size because of the extra strength furnished by the large number of tanks and the great seating capacity provided by them and by the thwarts 5' between them. Figures 9 and 10 illustrate how bread and water breakers 52 and 53 may be fitted in the thwarts. The removable tanks 34 of the form of lifeboat shown in Figure 7 may also serve as bread breakers.

If desired, any of the forms of lifeboat described above may be provided with scupper pipes, one of which is diagrammatically illustrated at 54 Figure 7.

In all of the constructions illustrated and described each tank should, of course, be provided with a manhole normally covered by a suitable water-tight cap so that access to the interior is possible. Such manholes are shown at 3! in Figure 4.

The regulations of the Bureau of Marine Inspection and Navigation also requires that each buoyancy tank in a lifeboat shall be provided with means for applying air-pressure to test its tightness. Therefore, each tank is provided with a nipple 38 to which an air-hose may be connected, and which is normally closed by a cap 39. I utilize this arrangement to also detect the presence of water in the tank by connecting to the part of the nipple on the inside of the tank a pipe or tube 40, which extends to the lowermost part of the tank as shown in Figure 14. With this arrangement air-pressure may he applied to the tank to test its tightness and also if there is any water in it, a certain amount will be ejected through the nipple 38 when the air-pressure is released. Then the manhole 31 may be opened and the water in the tank removed.

Also if desired the lifeboat may be provided with propelling means which I have indicated in Figures l, 3, 4 and 6, as consisting of pivoted handlevers 4i, connecting-rod d2, gears 33, propeller shaft 44, propeller 45, and reverse gear iii. This propelling mechanism, however, is not new and forms no part of the present invention. It is included to illustrate how well the internal shape of the lifeboat of this invention can accommodate mechanism of this character.

It will also be evident to those skilled in the art that the internal shape of this lifeboat is admirably suited for the installation of a motor, and also the radio-cabinet required in motor-propelled lifeboats without affecting in any way the construction of the air tanks.

1 claim:

1. In a lifeboat a sheet metal outer hull having curved ends, two identical sheet metal inner rull sections symmetrically positioned on opposite sides of the inside of said outer hull, each of said sections comprising a plurality of flat, straight sheet metal risers and flat straight sheet metal seat plates extending longitudinally of the outer hull parallel to the keel and terminating where they meet the curved ends of said outer hull, the adjacent edges of said risers and seat plates being connected together to form a series of ascending steps from a line adjacent to but spaced from the keel at which the lowest edge of the lowest riser is attached to the outer hull to a point adjacent the gunwale at which the back edge of the uppermost seat plate is attached to the outer hull, all of said points of attachment of said plates to each other and to the outer hull being airtight, and a flat sheet metal plate hermetically attached to the junction of each seat plate and the riser above it, and extending to the outer hull to which it is hermetically attached, said plates forming said inner hull section constituting with the outer hull the stiffening members of the lifeboat.

2. In a lifeboat, a sheet metal outer hull having curved ends, two identical sheet metal inner hull sections symmetrically positioned on opposite sides of the inside of said outer hull, each of said sections comprising a plurality of fiat straight sheet metal risers and flat straight sheet metal seat plates extending longitudinally of the outer hull parallel to the keel and ending where they meet the curved ends of said outer hull, the adjacent edges of said risers and seat plates being connected together to form a series of ascending steps from a line adjacent to but spaced. from the keel at which the lowest edge of the lowest riser is attached to the outer hull to a point adjacent the gunwale at which the back edge of the uppermost seat plate is attached to the outer hull, all of said points of junction of said plates to each other and to the outer hull being airtight, said plates forming said inner hull section constituting with the outer hull the stiffening members of the lifeboat, each of said risers and said seat plates being intersectible by an imaginary line drawn from keel to gunwale at right-angles to the length of the boat 3. In a lifeboat a sheet metal outer hull having curved ends, two identical sheet metal inner hull sections symmetrically positioned on opposite sides of the inside of said outer hull, each of said sections comprising a plurality of fiat straight sheet metal risers and fiat straight sheet metal seat plates extending longitudinally of the outer hull parallel to the heel and terminating where they meet the curved ends of said outer hull, said risers and seat plates being connected to form a series of ascending steps from a line adjacent to but spaced from the keel at which the lowest edge of the lowest riser is attached to the outer hull to a point adjacent the gunwale at which the back edge of the uppermost seat plate is attached to the outer hull, all of said points of attachment of said plates to each other and to the outer hull being airtight, and a fiat sheet metal plate hermetically attached to the junction of each seat plate and the riser, each of said last-mentioned flat sheet-metal plates lying approximately in a plane which if extended would intersect the center line of the lifeboat at approximately gunwale height.

4. In. a lifeboat a sheet metal outer hull having curved ends, two identical sheet metal hull sections symmetrically positioned on opposite sides of the inside of said outer hull, each of said sections comprising a plurality of fiat straight sheet metal risers and flat straight sheet metal seat plates extending longitudinally of the outer hull parallel to the keel and terminating where they meet the curved ends of said outer hull, said risers and seat plates being connected to form a series of ascending steps from a line adjacent to but spaced from the keel at which the lowest edge of the lowest riser is attached to the outer hull to a point adjacent the gunwale at which the back edge of the uppermost seat plate is attached to the outer hull, all of said points of attachment of said plates to each other and to the outer hull being airtight, and a fiat sheet metal plate hermetically attached to the junction of each seat plate and the riser, each of said last-mentioned flat sheet metal plates lying approximately in a plane which if extended would intersect the center line of the lifeboat at approximately gunwale height, each of said risers and said seat plates being intersectible by an imaginary line drawn from keel to gunwale at right-angles to the length of the boat.

5. In a lifeboat a sheet metal outer hull having curved ends, two identical sheet metal inner hull sections symmetrically positioned on the opposite sides of the inside of said outer hull, each of said sections comprising a plurality of flat straight sheet metal risers and flat straight sheet metal seat plates extending longitudinally of the said outer hull parallel to the keel and terminating where they meet the curved ends of said outer hull, the adjacent edges of said risers and seat plates being connected together to form a series of ascending steps from a line adjacent to but spaced from a keel at which the lowest edge of the lowest riser is attached to the outer hull to a point adjacent the gunwale at which the back edge of the uppermost seat plate is attached to the outer hull, all of said points of junction of said plates to each other and to the outer hull being airtight, the air-tank thus formed by said risers, seat plates and outer hull being divided into a plurality of air-tanks by spaced, fiat, sheet metal, transverse bulk heads extending from said risers and said seat plates to said outer hull and hermetically attached thereto, each 01' said risers and seat plates being intersectible by an imaginary line drawn from keel to gunwale at right- 5 angles to the length of the boat.

WILLIAM E. ELLING. 

